1. Field of the Invention
The present invention relates generally to devices for mixing and extruding plastically workable ingredients. More particularly the invention relates to a novel apparatus for producing moist clay by mixing water and dry powder and for automatically and continuously extruding the clay mixture into elongated cylindrically shaped extrusions, or logs.
2. Discussion of the Prior Art
Numerous types of dough type mixing devices for mixing water and dry powders to produce clay have been suggested. Similarly, various devices, generally known as "pug mills", have been devised for extruding the moist clay, or "pug" into cylindrical extrusions, or "logs". Generally, the prior art pug mills are unsatisfactory for the mixing operation due to their small size and due to the design of their impeller blades. Similarly, prior art mixing devices, while suitable for mixing, cannot be used for extruding the clay into a conveniently usable form.
The apparatus of the present invention is unique in that the initial operation of the device is that of a dough type clay mixer, while the secondary operation is that of a pub mill device.
The design of the device is such that either dry powder, or wet clay can be introduced into the mixing chamber. Mixing is accomplished by rotating the unitary shaft of the device in a first direction. So long as the shaft is rotating in this direction, the clay will be efficiently and effectively mixed by mixing blades of novel design. When the rotation of the shaft is reversed, the uniquely configured mixing blades will urge the clay mixture forwardly of the apparatus toward a helical screw or auger which carries it into a coaxially disposed extrusion chamber. The pug mill auger will then force the clay through a reduction cone and extrude it automatically and continuously into easy to handle logs, which may be formed into any desired shape.
The diameter of the mixing chamber of the apparatus is greatly enlarged over that of the pug mill to accomplish efficient and thorough mixing. By periodically adding water through the ample material inlet, the clay can be "held" in the mixing chamber for substantial periods of time. The clay can then be fed into the extruder as material is needed by the operator by simply reversing the direction of the motor which drives the common drive shaft. In essence, the apparatus of the invention embodies all the advantages of the prior art mixers and pug mills while effectively overcoming the drawbacks of each.
The most pertinent prior art of which the applicant is familiar and which serves to demonstrate the novelty of the present invention is as follows: U.S. Pat. No. 4,097,926--Face; U.S. Pat. No. 3,180,628--Pullin; U.S. Pat. No. 3,606,277--Kader; U.S. Pat. No. 3,145,977--August; U.S. Pat. No. 3,548,903--Holly; U.S. Pat. No. 842,206--Lowry; U.S. Pat. No. 3,323,570--Tullock et al.